They do make rodent guards for electric wires, but electric companies are loathe to let you fool with their wires.... Most will allow you to buy it, if you'll let them install them. And they will charge for that. And besides, the squirrels can always just climb right up the side of your house if they want to.

As far as the "bait" is concerned, whatever works. I have a friend (exterminator) that uses nothing but vanilla flavoring - and says he has no problem. Never tried it myself, not for squirrels, anyway. I have used it on mouse traps and it works with them, however. Me? For squirrels, I use strictly peanut butter in some form.